為了達成智慧型運輸系統的安全目標，車聯網的通訊需要滿足高可靠以及低延遲的需求，現行的技術中，能展現高可靠度的車聯網通訊系統為 3GPP 所提出的C­V2X(Cellular Vehicle to Everything)。C­V2X 的 mode 4 模式中，隱藏終端問題被認為會大幅降低車與車傳輸的可靠度，為了避免隱藏終端的發生，本文提出兩種方法針對發生隱藏終端的情況以及一種方法改善車輛壅塞的情況。研究發現車輛在道路上行進時，會因為傳輸範圍內車輛的變化以及車輛選擇無線電資源的時機而造成隱藏終端，本論文提出一種感知其他車輛的資訊來提前避免這些隱藏終端的方法。而本文也提出另一種只需額外傳送一點資訊就可以預測車輛之狀態來避免選擇相同無線電資源的狀況。此外，本論文提出改變車輛傳輸功率的方法用來改善車輛壅塞的情況，並透過模擬本論文所提的方法都能有效改善 C­V2X Mode4 的傳輸性能。

In order to achieve the safety goal of the smart transportation system, the communication of the Internet of Vehicles needs to meet the requirements of high reliability and low latency. Among the current technologies, the Internet of Vehicles communication system that can exhibit high reliability is the C­V2X (Cellular Vehicle to Everything) proposed by 3GPP. ). In C­V2X mode 4, the hidden terminal problem is considered to greatly reduce the reliability of vehicle­to­vehicle transmission. In order to avoid the occurrence of hidden terminals, this article proposes two methods for the occurrence of hidden terminals and one method to improve vehicle congestion condition. Research has found that when a vehicle is traveling on a road, hidden terminals will be caused due to the changes in the transmission range and the time when the vehicle selects radio resources. This paper proposes a method to perceive the information of other vehicles to avoid these hidden terminals in advance. This article also proposes another situation where the state of the vehicle can be predicted by simply sending a little additional information to avoid selecting the same radio resource. In addition, this paper proposes a method of changing vehicle transmission power to improve the situation of vehicle congestion, and by simulating the method proposed in this paper, the transmission performance of C­V2X Mode 4 can be effectively improved.

目錄
第一 章、緒論 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
第二 章、預備知識 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 相關文獻 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 C-­v2x Mode4 介紹 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
第三 章、改善 Hidden Terminal 的方法 . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Cooperative Selection Scheme(CoSS) . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Local Selection Scheme(LoSS) . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.3 預防車輛壅塞而導致碰撞之機制 . . . . . . . . . . . . . . . . . . . . . . . . 30
第四 章、模擬 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.1 模擬環境 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2 模擬結果之比較對象 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.3 資源池數量之結果 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.4 不同距離之結果 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.5 車輛環境中車輛的總數 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.6 車速變化 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.7 方法參數探討 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.8 壅塞狀況分析 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
第五 章、結論 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
參考文獻 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
附錄-­英文論文 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

圖目錄
Fig. 1 通道結構示意圖 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Fig. 2 SCI 內容圖 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Fig. 3 資源池示意圖 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Fig. 4 隱藏終端情境­相同重選計數器 . . . . . . . . . . . . . . . . . . . . . . . . 13
Fig. 5 隱藏終端情境­範圍內車輛變化 . . . . . . . . . . . . . . . . . . . . . . . . 14
Fig. 6 CoSS 之流程圖 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Fig. 7 CoSS 隱藏終端第一種情境 . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Fig. 8 CoSS 隱藏終端第二種情境 . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Fig. 9 隱藏終端情境­範圍外進入示意圖 . . . . . . . . . . . . . . . . . . . . . . . 26
Fig. 10 mode4 環境下距離變化之模擬結果 . . . . . . . . . . . . . . . . . . . . . 31
Fig. 11 模糊化流程 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Fig. 12 車子速度歸屬函數圖 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Fig. 13 車子數量歸屬函數圖 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Fig. 14 解模糊化的歸屬函數圖 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Fig. 15 歸屬函數圖之範例 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Fig. 16 歸屬函數圖之解模糊化範例 . . . . . . . . . . . . . . . . . . . . . . . . . 37
Fig. 17 根據資源池變化的碰撞率以及封包接收率模擬結果 . . . . . . . . . . . . 40
Fig. 18 根據傳輸距離變化的碰撞率以及封包接收率模擬結果 . . . . . . . . . . 41
Fig. 19 根據車輛總數變化的碰撞率以及封包接收率模擬結果 . . . . . . . . . . 42
Fig. 20 根據車輛最大速度變化的碰撞率以及封包接收率模擬結果 . . . . . . . . 43
Fig. 21 套用壅塞機制下資源池變化的碰撞率以及封包接收率模擬結果 . . . . . 46

表目錄
Table. 1 相關文獻之對應表格 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table. 2 CoSS 第一種隱藏終端情境之初始資訊表格 . . . . . . . . . . . . . . . . 19
Table. 3 CoSS 第一種隱藏終端情境之第一次傳輸資訊表格 . . . . . . . . . . . . 20
Table. 4 CoSS 第一種隱藏終端情境之第二次傳輸資訊表格 . . . . . . . . . . . . 21
Table. 5 CoSS 第二種隱藏終端情境之初始資訊表格 . . . . . . . . . . . . . . . . 22
Table. 6 CoSS 第二種隱藏終端情境之第一次傳輸資訊表格 . . . . . . . . . . . . 23
Table. 7 CoSS 第二種隱藏終端情境之第二次傳輸資訊表格 . . . . . . . . . . . . 24
Table. 8 動態資源池方法變數表格 . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table. 9 塞車模擬環境中判斷值 V 之碰撞率表格 . . . . . . . . . . . . . . . . . . 33
Table. 10 塞車模擬環境中判斷值 N 之碰撞率表格 . . . . . . . . . . . . . . . . . 34
Table. 11 壅塞等級對應傳輸距離之表格 . . . . . . . . . . . . . . . . . . . . . . . 38
Table. 12 根據 CoSS 方法中 Trc 變化之碰撞率模擬結果表格 . . . . . . . . . . . 43
Table. 13 根據 CoSS 方法中 Trc 變化之封包接收率模擬結果表格 . . . . . . . . . 44
Table. 14 根據 LoSS 方法中公式中 α 變化之碰撞率模擬結果表格 . . . . . . . . 44
Table. 15 根據 LoSS 方法中公式中 α 變化之封包接收率模擬結果表格 . . . . . . 45
Table. 16 根據 LoSS 方法中公式中 β 變化之碰撞率模擬結果表格 . . . . . . . . 45
Table. 17 根據 LoSS 方法中公式中 β 變化之封包接收率模擬結果表格 . . . . . . 45

[1] Wantanee Viriyasitavat, Mate Boban, Hsin­Mu Tsai, and Athanasios Vasilakos. ”Vehicular
Communications: Survey and Challenges of Channel and Propagation Models”, 2015.
[2] Shanzhi Chen, Jinling Hu, Yan Shi, and Li Zhao. ”LTE­V: A TD­LTE­Based V2X Solution
for Future Vehicular Network”, 2016.
[3] ” 5GAA Releases White Paper on C­V2X Use Cases: Methodology, Examples and Service Level Requirements”. https://5gaa.org/news/
5gaa-releases-white-paper-on-c-v2x-use-cases-methodology-examples-and-service-level-requirements/.
[4] Le Wang, Renato F. Iida, and Alexander M. Wyglinski. ”Performance Analysis of EDCA
for IEEE 802.11p/DSRC Based V2V Communication in Discrete Event System”. In 2017
IEEE 86th Vehicular Technology Conference (VTC­Fall), pages 1–5, 2017.
[5] Daniel Jiang and Luca Delgrossi. ”IEEE 802.11p: Towards an International Standard
for Wireless Access in Vehicular Environments”. In VTC Spring 2008 ­ IEEE Vehicular
Technology Conference, pages 2036–2040, 2008.
[6] 3GPP. ”Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal
Terrestrial Radio Access Network (EUTRAN); Overall description; Stage 2.”. Technical
Specification (TS) 36.300, 3rd Generation Partnership Project (3GPP), 09 2016. Version
14.0.0.
[7] 3GPP. ”Study on enhancement of 3GPP Support for 5G V2X Services”. Technical Report
(TR) 22.886, 3rd Generation Partnership Project (3GPP), 03 2017. Version 15.1.0.
[8] ” An assessment of LTE­V2X (PC5) and 802.11p direct communications technologies for improved road safety in the EU”. https://5gaa.org/news/
an-assessment-of-lte-v2x-pc5-and-802-11p-direct-communications-technologies-for-improved-road-safety-in-the-eu/.
[9] Rafael Molina­Masegosa and Javier Gozalvez. ”LTE­V for Sidelink 5G V2X Vehicular
Communications: A New 5G Technology for Short­Range Vehicle­to­Everything Communications”, 2017.
[10] Rafael Molina­Masegosa and Javier Gozalvez. ”System Level Evaluation of LTE­V2V
Mode 4 Communications and Its Distributed Scheduling”, 2017.
[11] Bo Gu, Xu Zhang, Ziqi Lin, and Mamoun Alazab. ”Deep Multiagent ReinforcementLearning­Based Resource Allocation for Internet of Controllable Things”. IEEE Internet
of Things Journal, 8(5):3066–3074, 2021.
[12] Odilbek Urmonov and HyungWon Kim. ”Multi­Agent Deep Reinforcement Learning
Based Distributed Resource Allocation”. In 2021 IEEE International Symposium on Circuits and Systems (ISCAS), pages 1–5, 2021.
[13] Rafael Molina­Masegosa, Javier Gozalvez, and Miguel Sepulcre. ”Configuration of the
C­V2X Mode 4 Sidelink PC5 Interface for Vehicular Communication”. In 2018 14th International Conference on Mobile Ad­Hoc and Sensor Networks (MSN), pages 43–48, 2018.
[14] Alessandro Bazzi, Giammarco Cecchini, Alberto Zanella, and Barbara M. Masini. ”Study
of the Impact of PHY and MAC Parameters in 3GPP C­V2V Mode 4”. IEEE Access,
6:71685–71698, 2018.
[15] Luis F. Abanto­Leon, Arie Koppelaar, and Sonia Heemstra de Groot. ”Enhanced C­V2X
Mode­4 Subchannel Selection”. In 2018 IEEE 88th Vehicular Technology Conference
(VTC­Fall), pages 1–5, 2018.
[16] Yongseok Jeon, Seungho Kuk, and Hyogon Kim. ”Reducing Message Collisions in
Sensing­Based Semi­Persistent Scheduling (SPS) by Using Reselection Lookaheads in
Cellular V2X”. Sensors, 18(12), 2018.
[17] Nestor Bonjorn, Fotis Foukalas, Ferran Cañellas, and Paul Pop. ”Cooperative Resource
Allocation and Scheduling for 5G eV2X Services”. IEEE Access, 7:58212–58220, 2019.
[18] So­Yi Jung, Hye­Rim Cheon, and Jae­Hyun Kim. ”Reducing Consecutive Collisions in
Sensing Based Semi Persistent Scheduling for Cellular­V2X”. In 2019 IEEE 90th Vehicular Technology Conference (VTC2019­Fall), pages 1–5, 2019.
[19] Byungjun Kang, Sunghoon Jung, and Saewoong Bahk. ”Sensing­Based Power Adaptation
for Cellular V2X Mode 4”. In 2018 IEEE International Symposium on Dynamic Spectrum
Access Networks (DySPAN), pages 1–4, 2018.
[20] R. Molina­Masegosa, M. Sepulcre, and J. Gozalvez. ”geo­based scheduling for c­v2x
networks”, 2019.
[21] X. Gu, B. Leng, L. Zhang, J. Miao, and L. Zhang. ”a stochastic geometry approach to
model and analyze future vehicular communication networks”, 2020.
[22] P. Wendland and G. Schaefer. ”feedback­based hidden­terminal mitigation for distributed
scheduling in cellular v2x”, 2020.
[23] X. He, J. Lv, J. Zhao, X. Hou, and T. Luo. ”design and analysis of a short term sensing
based resource selection scheme for c­v2x networks”, 2020.
[24] Y. Jeon and H. Kim. ”an explicit reservation­augmented resource allocation scheme for
c­v2x sidelink mode 4”, 2020.
[25] ETSI. ”LTE; Evolved Universal Terrestrial Radio Access (E­UTRA); Multiplexing and
channel coding ”. TECHNICAL SPECIFICATION(TS) 136 212, 3rd Generation Partnership Project (3GPP), 4 2017. Version 14.2.0.
[26] Zahid Khan, Pingzhi Fan, Fakhar Abbas, Hongyang Chen, and Sangsha Fang. Two­level
cluster based routing scheme for 5g v2x communication. IEEE Access, 7:16194–16205,
2019.
[27] Tomoki Maruko, Shinpei Yasukawa, Riichi Kudo, Satoshi Nagata, and Mikio Iwamura.
Packet collision reduction scheme for lte v2x sidelink communications. In 2018 IEEE
88th Vehicular Technology Conference (VTC­Fall), pages 1–5, 2018.